Many food and beverage products include chemical preservatives to extend the shelf-life of the product by inhibiting the growth of spoilage microorganisms (e.g., mold, yeast, bacteria) in the product for an extended period of time. However, some preservatives currently in use have been found to have detrimental health and/or environmental effects, or are not sufficiently stable. Therefore, there is market demand for food and beverage products which do not include these detrimental preservatives, and yet still possess extended shelf-life. There is also consumer demand for natural ingredients in food and beverage products.
For example, benzoic acid and its salts are commonly used in beverage products as preservatives. However, benzoic acid and its salts can react with ascorbic acid (Vitamin C), to form benzene, which is a carcinogen. Heat and light increase the rate of this reaction, so production and storage of beverage products under hot or bright conditions speeds up formation of benzene. Intake of benzene in drinking water is a public health concern, and the World Health Organization (WHO) and several governing bodies including the United States and the European Union have set upper limits for benzene content in drinking water of 10 ppb, 5 ppb, and 1 ppb, respectively.
Ethylenediamine tetraacetic acid (EDTA) and its salts is another common beverage product preservative. EDTA is a metal ion chelator that sequesters metal ions and prevents their participation in catalytic oxidation reactions. EDTA at elevated concentrations is toxic to bacteria due to sequestration of necessary metals from the outer membrane of bacteria. However, EDTA is not bio-degradable, nor is it removed during conventional wastewater treatment. Recalcitrant chelating agents such as EDTA are an environmental concern predominantly because of their persistence and strong metal chelating properties. Widespread use of EDTA and its slow removal under many environmental conditions has led to its status as the most abundant anthropogenic compound in many European surface waters. River concentrations in Europe are reported in the range of 10-100 μg/L, and lake concentrations are in the range of 1-10 μg/L. EDTA concentrations in U.S. groundwater receiving wastewater effluent discharge have been reported in the range of 1-72 μg/L, and EDTA was found to be an effected tracer for effluent, with higher concentrations of EDTA corresponding to a greater percentage of reclaimed water in drinking water production wells.
The presence of chelating agents in high concentrations in wastewater and surface water has the potential to remobilize heavy metals from river sediments and treated sludge, although low and environmentally relevant concentrations seem to have only a very minor influence on metal solubility. Elevated concentrations of chelating agents enhance the transport of metals (e.g., Zn, Cd, Ni, Cr, Cu, Pb, and Fe) in soils and enhance the undesired transport of radioactive metals away from disposal sites. Low concentrations of chelating agents may either stimulate or decrease plankton or algae growth, while high concentrations always inhibit activity. Chelating agents are non-toxic to many forms of life upon acute exposure; the effects of long-term low-level exposure are unknown. EDTA ingestion at high concentrations by mammals changes excretion of metals and can affect cell membrane permeability.
Polyphosphates are another common beverage product preservative. However, polyphosphates are not stabile in aqueous solution and degrade rapidly at ambient temperature. Degradation of polyphosphates results in unsatisfactory sensory issues in the beverage product, such as change in acidity. Also, the shelf-life of the beverage product is compromised because of the reduced anti-microbial action from the reduced concentration of polyphosphate.
It is therefore an object of the present invention to provide new preservative systems for use in beverages as full or partial replacements for at least one currently used preservative that has detrimental health and/or environmental effects, or lack of sufficient stability. It is further an object of the invention to provide new beverage preservative systems with improved sensory impact. It is further an object of the invention to provide preservative systems without benzoic acid and/or reduced concentrations of sorbic acid. Some countries have regulatory restrictions on the use of sorbic acid in food and beverage products wherein the permitted concentration is less than the amount required to inhibit the growth of spoilage microorganisms by itself.
It is further an object of the invention to identify a sequestrant which is bio-degradable and can be substituted for EDTA. It is further an object of the invention to identify a sequestrant which is stable to heat in aqueous solution and can be substituted for polyphosphates. The invention is novel and unique in that only a very limited number of known compounds are able to complex metal ions so as to make the metal unavailable for use by spoilage microorganisms, but do not cause measurable concern to health and nutrition experts. The odds that any such compound will also fall within the constraints on sensory impact in a beverage is on the order of 1:1000 to 1:10,000.